The invention relates to anti-theft locking arrangements, and more particularly to locking arrangements for prevention of the unauthorized coupling of truck tractors and truck trailers.
The standard mechanism used to couple truck tractors and trailers includes a fifth-wheel mounted on the truck tractor and a king-pin mounted on the trailer. Typically, the king-pin extends downwardly from the trailer and has an annular groove located around the outer surface of the king-pin. The fifth-wheel has a slot or a set of jaws which are adapted to engage the grooved king-pin.
The trucking industry has standardized the coupling mechanism between truck tractors and trailers allowing any tractor having a fifth-wheel to engage any trailer having a fifth-wheel. A problem associated with the convenience of standardization, however, is the theft of trailers. Because one practice of the trucking industry is to leave trailers in unprotected parking areas for pick up by truck tractors, standardization of tractor-trailer couplings has facilitated the theft of trailers. A thief having a truck tractor equipped with a standardized fifth-wheel can couple the truck tractor with an unattended trailer and drive away with the trailer and its contents.
Various locking arrangements for the prevention of unauthorized coupling of a fifth-wheel of a tractor to the king-pin of a trailer have been developed. Prior locking arrangements have had the undesirable characteristics of being excessively heavy or ineffective. Additionally, prior locking arrangements have embodied relatively complex designs which are relatively expensive to produce.